Switch device



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F.. Foss 1.',8-64Q53-2v SWITCH DEVICE l* `Filed Aug. 5. 1929 3 Sheets-Sheet l June 28, 1932. F., yfr, FQRSg, 1,864,532

` SWITCH DEVICE" Filed Aug. 5, 1929 25 Sheetmwez 2 J9 @Cf Big5 June 28, 1932. 5:, p FQRSS SWITCH DEVICE Filed Aug. 5, 192@ 3 Sheets-Sheet 5 JO Z6 Patented June 28, 1932 UNITED STATES PATENT OFFICE FRITHIOF P. FORSS, OF AURORA, ILLINOIS, ASSIGNOR T0 INDEPENDENT PNEUMA'IIC TOOL COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE swircn DEVICE Application led August 5, 1929. Serial No. 383,643.

This invention relates to improvements in electric switches and more particularly to switches which are employed in portable electric tools such as drills, reamers, screw and nut drivers, grinding machines and the like.

One object of my invention is to have all -of the switch parts of ample dimensions so as to withstand the maximum number of operations employed in turning on and off the switch which operations in portable tools in the kind referred to are several hundred and even a thousand and more times during' each working day.

A further object of my invention is to provide a switch which is particularly adapted to ortable electrically driven tools of a size which can be held in one hand while operating them.

A further object of my invention is to have the switch mechanism so designed that it will fit in the end of the tool which is held in the hand and can be readily and easily operated at the same time that the tool is placed against the work.

A further object of my invention is to provide a switch mechanism which conforms to the general contour of the tool and be within the diameter of the. tool casing so that no pro jections are provided to interfere with the hand of the operator gripping and handling the tool.

The switch mechanism of my invention is particularly designed not only to conform to the end of the tool which is grasped and held by the operator but is also designed to fit about the portion of the armature shaft of the motor at such end of the tool and thus take advantage of the fairly large diameter to provide the switch of ample dimensions as to withstand the repeated operations to which the switch is subjected.

The invention consists further in the matters hereinafter described and claimed.

In the accompanying drawings:

Fig. l. is a side view of ay portable electric tool embodying the switch mechanism of my invention;

Fig. 2 is a vertical sectional view taken through the upper end of the tool to show my improved switch mechanism;

Fig. 3 is a horizontal sectional view taken on line 3--3 of Fig. 2, the switch being shown type and of the size which can be readily and v easily held in and operated by one hand. The switch mechanism of my invention is particularly adapted for such tools and is so designed as to be located at the end of the tool which is held in the hand without increasing the outer diameter of the tool to interfere with the ease of handling and operating the tool. The switch mechanism is further designed to have its operating member so arranged that it can be readily and easily engaged by the lingers of thehand which holds the tool and permit the latter to be operated with ease and conveniently.

The tool as shown in Fig. 1 has an outsideA casing 1 generally cylindrical in shape and in which is located the electric motor 2 which furnishes the power for the tool. The upper end of the casing l is closed by cap 3 which forms an upward continuation of the casing l and has substantially the same outside diameter so as not to project beyond the casing to interfere with the operator grasping and holding the tool over its upper end. The cap 3 provides a chamber tin which the switch mechanism of my invention is housed. The armature shaft 5 of the motor 2 has its upper end portion extending centrally through the chamber 4 and is journaled in the closed end of the cap in an anti-friction bearing 6, as shown in Fig. 2.

The switch, mechanism of my invention comprises a circular base plate 7 which has a centrally disposed, upwardly extending, tubular projection 8 through which the shaft 5 extends. vThe projection 8 has an inside diameter slightly greater than the diameter of the shaft so that the latter may run free in the projection with suiicient clearance to avoid accurate mounting and machining of the mechanism. The plate 7 is supported on and secured to an inwardly extending flange 9 at the upper end of the casing 1 by a suitable numberof screws, some of which are long enough to pass through the cap to also secure it in place.

The switch mechanism includes an outer ring member 10 and an inner ring member 11, the latter being concentric with respect to the outer ring member, and rotatably mounted therein on the tube 8. The tube 8 is provided with an annular seat 12 to support the ring 11 above the plate 7. The ring 11 is held against upward movement by a washer 13 which is retained in place on the tube 8 by a split spring ring 14.

Two pairs of contacts, with the contacts of each pair consisting of members 15, 16, are fastened to the stationary ring 10 in vertical spaced relation, as shown in Fig. 2. The movable ring 11 is provided with a handle 17 arranged in the plane of the ring and extending outward therefrom through an elongated slot 18 in the stationary ring 10 so that the movable ring 11 may be rotated within the limits as defined by the length of the slot. The handle 17 projects outward from the cap 3 through a slot 19 therein so that the handle may be engaged for operating the switch.

The movable ring 11 carries a pair of spring pressed contacts 20, 2O which when the switch is in on position, (Fig. 3) bridge the respective pair of stationary contacts 15, 16 as shown in Fig. 2. Each Contact 20 comprises a boX type plunger, the side walls 21 of which have a sliding t in parallel slots 22, 22 in the ring 11 and extending therethrough from top to bottom. The portion 23 of the ring between the slotsterminates short of the periphery of the ring so that the plunger 2O may come flush with the periphery of the ring, there being a light coil spring 24: between the parts to normally urge the plunger outward and keep it in contact with the inner surface of the stationary ring 10 for bridging the respective pair of contacts 15, 16 when the switch is turned into on position. By the structure described, the flow of current through the movable contact 20 is only through the plunger and not through the spring, thereby avoiding heating of the spring to weaken it as the stationary ring 10 as shown in Fig. 2.

The screws referred to pass through the last mentioned ring.

To produce a quick snap action for the switch as the movable ring 11 is rotated into its on and off positions and also to hold the ring against accidental rotation in such positions, I provide a cooperating plunger and cam action as follows. The ring 11 is provided at one point in its circumference, preferably opposite the contacts 20, with a cam member 25 preferably made integral with the ring and within the periphery of the same. Recesses or depressions 26, 26 are made in the periphery of the ring 11 on opposite sides of the cam 25 so as to receive the adjacent end of the spring pressed lplunger 27 which is mounted in the stationary rlng 10 and projects inward of the inner circle thereof, as shown in Figs. 3 and 4. The plunger 27 is mounted for sliding` movement within a recess 28 formed in the stationary ring 10 and a coiled ex ansion spring 29 is located in said recess an engages the lunger to normally urge it toward the mova le ring 11. The outer end of the plunger and the recesses or depressions 26 are made complementary so that the plunger will fit into the recess and thus hold the ring 11 against accidental movement when the switch is in either its on or ofi position. It is preferable that the plunger a d the recesses be made semi-spherical in ape so that the plunger will act as a guide for the ring and hold it central with respect to the stationary ring 10 and also hold the ring 11 from lateral movement with respect to the ring `10. This will avoid the necessity of anv tight clamping of the movable ring 11 within the stationary ring 10 and thus avoid undue friction to the free and easy movement of the movable ring 11 in the operation ofthe switch.

The sides of the cam 25 are formed by the adjacent portions of the recesses 26, 26 and the inclination is approximately seventy-five degrees so that the plunger 27 when riding up on either incline will resist the turning o the ring 11 until the plunger rides over the high point or top of the cam 25 whereupon the ring will be given a quick Isnap aetion as the plunger rides down the opposite side of the cam thereby producin Y a quick breaking between the movable and xed contacts heretofore described to prevent destructive arcing.

Vith the cam 25 carried by the movable ring 11 and not projecting beyond the periphery thereof` the diameter of the ring 11 is not increased with the result that 'the iuner surface of the stationary ring 1() may be brought relatively close to the ring ll 'and thereby permit the parts to be made of ample dimensions to withstand the repeated movementof the switch into its on and off positions. Moreover the `ltatiouary ring 10 magv be given the dimensions required so that t e working parts may be given the required size and st-rength for a switch device of ythis character and also to provide ample material in the stationaryl ring to support the screws` and bolts which are required. to fasten the switchfassembly in its housin Y 3 at the upperend of the tool. The ring lObeingl so made also allows-the necessary opening 30 to be formed therein to accommodate the lead-in wires which 'supply the current to the motor of the tool.-

The movable contacts 20, 2O are mounted so that they have a slight movement both laterally and longitudinally so asto compensate for and automaticallyadjust themselves to the deformation of the surfaces against which they contact, due to wear. This is brought about by having sufficient play between the side walls 21 of the movable contacts and the slots 22 into which said side walls extend and also due tothe central position of the sprin 24 which serves as a pivot for the longitudinal movement of the contact.

To prevent wedging or binding of the movable contacts With' respect to `the fixed ones, the movable contacts 20 are made long enough toextend above andbelow the fixed contacts l5, 16 and thus `have .their upper andlower edges sufiiciently removed from the fixed contacts to prevent wearing wedge shaped grooves into them. vWith the movable contacts 20 of this length, the stationary ring 10 below the lower fixed contact 16 is counterbored, as at 31, so that sufficient clearance is provided to prevent the lower edge of the movable contacts from engaging the ring and keeping said contacts out o proper engagement with the fixed ones during the operation of the switch.v

The portion of the yring 10 above the counterborely is substantially flush with the inner edges of the fixed contacts 15, 16 so as'to provide a continuous and unbroken surface about the entire circumference ofthe-ring where the movable contacts engage and thus present no obstacles or projections to inter-I fere with the action of the movable ring 11 and also to allow the movable contacts tobe moved into and off of the fixedcontacts without interference and also to prevent any working action of the spring 24. With this continuous surface, the Wear on all parts thereof is even and no opportunity7 is. afforded for the movable contacts to fail t0 bridge the fixed ones because the latter are atall times maintained fiush with the surface referred to and the movable contacts will properlvbridge the fixed ones whether the Wear is on one or the other or both.r This continuous surface also provides an even support preventing compression or expansion of the spring 24, thereby prolonging tbe life of the spring as the radius of this surface remains substantially constant The switch mechanism shown and described is particularly applicable for a three phase motor such as is employed in portable tools of the character heretofore referred to. The wiring diagram for the switch is shown in Fig. 6. There, .the three lead-in Wires are indicated by 32, 33am] 34, respectively. The Wires 32, 33 are connected to the upper fixed contacts 15, `15 of each set. The Wire 34 is connected to a stud 35 carried by the stationary' ring l0. A wire 36 connectsk this stud with one lead Wire of the motor which is shown diagrammatically in the figure and indicated by 2. Wires 37, 38 connect the` other of the two lead wires of the motor with the lower fixed contacts 16, 16 of the two sets. The movable contacts Q0 are illustrated diagralmnatically in this figure and are shown in position to be moved into and out of' on and off position when the movable ring 11 is turned as heretofore described. By the wiring diagram illustrated, it will be noted that when the movable contacts are moved out of bridging engagement with the fixed contacts 15, 16 of each set the current is broken through two of the wires due to the fact that the 'movable contacts constitute a section of these wires.

The switch mechanism of my invention is rugged and strong and has parts of ample dimensions to withstand the repeated operation thereof in service and as heretofore stated is designed to fit in the end of the motor casing Where the leading wires are attached and also conform to the general shape of the motor casing and thus keep the tool substantially uniform in diameter and of' a `Character which may be readily engaged by the hand of the operator when transporting and using the tool. p ,f

The 4details of construction and arrangement of parts shown and described may be various changed and modified without departing from the spirit andscope of my invention.

Ifclaim as my invention: f

1.l A switch device of the character described, comprising' a pair of inner and outer ring membersof insulating material, one of said ring members beingrotatably mounted With respect to the other ring member, a pair of spaced contacts carried by one ring member, and a bridging contact carried by the other ring member. and spring means serving to urge the bridging contact toward the spaced ones and being outside of the Circuit passing'through the contacts when engaged.

2. A switch device of the character described, comprising a pair of inner and outer ring members of insulating material, one of said members being'rotatably mounted, with respect tothe other ring member, a pair of parallel contacts carried by one of said members and spaced apart in the direction of the axis of the rotatable member, and a single Cfr Cal

Contact carried by the other member and disposed parallel to the axis of the rotatable member and arranged to bridge the other contacts at the same time when the rotatable member is moved to engage the contacts.

3. A switch device of the character described, comprising a pair of inner and outer ring members of insulatiner material, one of said members being rotatably mounted with respect to the other ring member, spaced contacts carried by one of the members, a bridging contact for said spaced contacts and carried bythe other member, and means for imparting a quick snap action to the rotary member in engaging and disengaging the contacts .4. A switch device of the character described, comprising a pair of inner and outer riiw members of insulating material, one of said ring members being rotatably mounted with respect to the other ring member, contacts carried by the respective members, a cam carried by'one of said members, and a spring pressed plunger carried by the other oit the members, said plunger acting on said cam to produce a quick snap action to the rotary member as the plunger passes over the high point of the cam in the engaging and disengaging of the contacts.

5. A switch device of the character described, comprising a pair of inner and outer ring members of insulating material, one ring member being rotatably mounted with respect to the other ring member, contacts carried by the respective members, a cam carried by one member and having depressions on opposite sides of the same, a spring pressed plunger carried by the other member and adapted when engaged in said depressions to limit the throw of the rotary member, said plunger acting on the cam as it passes over the high point thereof to impart a quick snap rotation to the rotary member to engage and disengage the contacts.

6. A switch device of the character described, comprising a pair of inner and outer ring members of insulating material, one of said members being rotatable with respect to the other ring member, contacts carried by the respective members, a pair of depressions in the periphery of one of said members and providing between them a cam, a spring pressed plunger carried by the other member and operating on said cam in the rotation of the rotary member to impart a quick snap rotation thereto to engage and disengage the contacts, and stop means for limiting the throw of the rotary member.

T. A switch device of the character de scribed. comprising a supporting base having a lateral shaft extension, a pair of inner and outer ring members of insulating material surrounding said extension with the inner ring member rotatably mounted thereon and the outer ring member fixed to said supporting base, contacts carried by said ring members, and means whereby the inner ring member may be rotated with respect to the other one to engage and disengage said contacts.

8. A switch device of the character described, comprising a supporting base having a lateral shaft extension, a pair of inner and outer ring members surrounding said extension with the inner ring member rotatably mounted thereon and the outer ring member fixed to said base, contacts carried by the inner and outer ring members, and a handle carried by the inner ring member whereby the latter may be rot-ated to effect engagement and disengagement ot said contacts, said outer ring member having a slot therein to accommodate the handle and form stops to limit the movement of the inner ring member.

9. A switch device of the character described, comprising a. supporting base having a lateral shaft extension, inner' and outer ring members surrounding said extension with the inner ring member rotatably mounted thereon and the outer ring member fixed to said base, said extension having an annular seat for said inner ring member, a-

means at the outer end of the extension to prevent displacement of the inner ring member from said seat, contacts carried by the respective ring members, a handle on the inner ring member whereby it may be rotated to engage and disengage the contacts, and stop means for the handle on the outer ring member to limit the throw of the inner ring member.

10. A switch device of the character described, comprising a supporting base havin lateral shaft extension, a pair of inner an( outer members of insulating material surrounding said extension with the inner ring member rotatably mounted thereon and the outer ring member fixed to the base, a pair of stationary contacts carried by the outer ring member and spaced apart axially of the rotary ring member, and a bridging contact for the spaced ones and carried by the. rotary ring member, said bridging contact having a length to extend between and beyond the spaced contacts, and said inner ring member having its inner' circle -counterbored between the supporting base and the adjacent stationary contact.

l1. `A switch device of the character described, comprising a supporting base having lateral shaft extension. a pair of inner and outer ring members of insulating material surrounding said shaft with the inner ring member rotatably mounted thereon and the outer ring member secured to said base, contacts carried b v the respective-ring members for engagement and disengagement in the rotation of the inner ring member, a cam member at the periphery of the inner ring member and depressions on opposite sides of ascuas 5 the same and a spring pressed plunger carried by the outer ring member and cooperating with said cam to effect a quick snap movement to the inner ring member when 1t is ro- 5 tated to engage and disengage the contacts, the depressions and the ends of the plunger cooperatin therewith being made in semispherical orm so as to center the inner ring member and hold it from displacement on 1 said shaft.

12. A switch device of the character described, comprising a air of inner and outer rin members of insu atin material, one of sai members being rotata ly mounted with l5 respect to the other, two pairs of spaced cony tacts carried by one ring member, a pair of brid ing contacts for the spaced contacts carried y the other ring member, means for im l, parting a quick snap action to the rotatable 20 ring member when actuated to en age and disengage the contacts, and a stu carried by the stationary ring whereby the swltch device may be connected with a three phase motor circuit.

13. A switch device of the character described, comprising a pair of inner and outer ring members of insulating material, one ring member bein rotatable with respect to the other, a pair o non-resilient spaced con- 80 tacts carried by one ring member, a brid ing contact carried by the other ring mem er Said bridging Contact being slidably carried by the r1ng on which it 1s mounted, and spring means for urging said bridging con- 85 tact toward the spaced ones. v

14. A switch device of the character described, comprising a supporting base havin lateral shaft extension, a air of inner and outer rin members rotatab y mounted there- (0 on and t e outer ring member fixed to the base, a air of non-resilient spaced contacts carried y the outer ring member and conformin to the inner surface thereof, and a single ridging contact for the spaced con- 46 tacts and carrled by the inner member, the surface of the inner ring member being iiush with the adjacent edges of the spaced contacts so as to rovide a smooth and continuous bearing for t e bridging contact in its move- 50 ment into and out of engagement with the spaced contacts, and s ring means carried by the inner ring mem r and engaging the single contact to hold said contact in engage'- s ment with said surface.

l5 In testimony whereof I aix my signature.

FRITHIOF P. FORSS. 

